Dragon Infusion Perk?

Just what does the Dragon Infusion perk do?

For those of you who don't know what I'm asking it's a Misc Quest for Esbern during the Dragonborn questline just before you fight Alduin on the Throat of the World right after you obtain Dragonrend. When you go Sky Haven Temple and Esbern and Delphine are outside, Esbern speaks of a dream he had depicting a certain dragon perch (it's random but from my experience its always at the Skyborn Altar). You go there, kill the dragon, and then return to Esbern telling him you killed the dragon there he will then ask you to bring him a dragon bone and a scale. Once you give them those items he makes a potion that gives you this perk I'm inquiring about.